1. Field of the Invention
The invention relates to a process for the production of lactic acid from the rumen contents of cattle or sheep collected during slaughter.
2. Description of the Prior Art
Waste from the slaughter of cattle and sheep poses a significant health and disposal problem for slaughter houses. Rumen contents, which comprise a substantial fraction of this waste, care currently of little if any value to the industry. Typically, slaughter plants collect the rumen contents from the animals as a separate by-product from the line. The line portion is removed and disposed of as liquid waste. In some locations, the solids may be spread on land or given to beef cattle feedlots. However, in other locations, slaughter plants must pay for disposal of the solids.
Lactic acid is used commercially in a wide variety of applications. Several of these applications include use in the textile industry as a mordant or solvent when dyeing and for reducing chromates in mordanting wool, as a confectionary, in cheese making, in brewing as an acidulant, in the tanning industry for dehairing, plumping and decalcifying hides, in pharmacy as an acidulant, irrigant or antiseptic, and in organic synthesis such as the manufacture of lactates [The Merck Index, Eleventh Edition, Budavari et al. (ed.), Merck & Co., Inc., Rahway, N.J., 1898, p. 5214].
Conventional processes for the manufacture of lactic acid have relied upon fermentation of carbohydrates by a number of different lactic acid bacteria or by direct chemical synthesis. The lactic acid bacteria are generally recognized as those gram-positive bacteria that produce lactic acid as a major or sole product of fermentative metabolism. They belong to the genera Lactobacillus, Streptoccoccus, Leuconostoc, and Pediococcus. Most commonly, these fermentations have employed cultures of Streptococci, or Lactobacilli such as Lactobacillus delbrueckii, L. casei, L. bulgaricus or L. acidophilus, or other bacteria such as Bacillus acidilacti. Traditional substrates used in these fermentations include milk, whey, cornstarch, potatoes and molasses.
Gomez-Hernandez and Coronado-Vega disclosed the production of lactic acid by anaerobic fermentation with a complex mixture of microorganisms as an inoculum [Biotechnology Letters, 5(9):629-632, (1983)]. Using cow manure to inoculate a culture medium, lactic acid production could be effected by maintaining the pH at relatively high levels.